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Objectives. To determine whether NART scores are associated with severity of brain injury and therefore presumably affected by brain injury. In addition, to compare the Cambridge Contextual Reading Test (CCRT) with injury severity in head-injured individuals.
Design and methods. Participants were 55 survivors of traumatic head injury, who completed the NART and the CCRT The scores on these premorbid measures were then compared with indices of injury severity from their initial neurosurgical admission.
Results. The NART was significantly correlated with Glasgow coma scale, with greater severity of injury associated with poorer performance. Poorer NART performance was also significantly more likely amongst those whose injury resulted in coma. The CCRT was preferred by patients, though it was also significantly associated with Glasgow coma scale and presence of coma.
Conclusions. The data suggest that performance on both the NARTand the CCRT are affected by brain injury severity and thus may underestimate true premorbid ability in these individuals. Similar findings would be likely with the conceptually identical WTAR measure. These measures should be used with appropriate caution and may be usefully supplemented by predictions based on demographic information.
The National Adult Reading Test (NART), which assesses the pronunciation of 50 irregularly spelt words, is -widely used as an estimate of an individual's intelligence before the onset of dementia or other neurological insult (Nelson & Willison, 1991). Such measures of premorbid intelligence must correlate highly with measured IQ in the healthy population and be resistant to neurological or psychiatric disorder. The use of the NART as a measure of premorbid intelligence was initially based upon the observation that reading ability is relatively well preserved in individuals with dementia (Nelson & McKenna, 1975), but the NART has become used as the standard measure of premorbid intelligence across a range of neuropsychiatric conditions (O'Carroll, 1995). The more recent Wechsler Test of Adult Rending (WTAR) is a very similar premorbid measure based upon the same concept as the NART.
Its role as a valid measure of premorbid intelligence following closed head injury has been supported by two studies, which found no significant differences in NART performance between head-injured patients and well-matched controls (Crawford, Parker, & Besson, 1988; Watt & O'Carroll, 1999). Additionally, a case study in which the NART error score...